The increased aluminium (Al) levels in serum of patients with chronic renal failure on hemodialysis are associated with impaired erythropoiesis and iron metabolism. The long term Al loading of rats (20 to 90 days) has similar effect. Data are still lacking about the effects after short-term aluminium treatment. The 7 day's treatment with Al2(SO4)3 in a dose 67.5 mg/kg b. w., i. m. m. significantly decreased hemoglobin, hematocrit, incorporation of 59Fe in newly formed erythrocytes and increased reticulocytes in absolute and relative counts. We observed a mild degree hypochromic, ferropenic, microcytic anemia and polychromazia in the available macrocytes. The immature erythroblasts were predominant forms in the erythroblastogram while the number of mature erythroblasts was decreased. Index of maturation of erythroblasts was lower, indicating inhibited erythroblast maturation. Plasma iron, TIBC, transferrin saturation and 59Fe absorption in the experimental group were significantly decreased. Spontaneous and mechanical hemolysis of erythrocytes were lower while erythrocyte deformability was increased. Obviously, Al treatment inhibits erythropoiesis and iron metabolism, probably hinders hemoglobin synthesis and erythroid cell maturation but does not affect the studied functional characteristics of mature erythrocytes negatively.